The present invention relates to a system, method, network elements, and computer program products, for providing a service such as a supplementary service. The service may preferably be provided with or for another service such as a communication service which may e.g. be a voice communication service, a data communication service, a multimedia communication service, etc. The service may preferably be provided using preconditions. The supplementary service and the communication service are provided in a communication network with a suitable protocol, preferably Session Initiation Protocol, SIP, and preferable in a SIP network such as the IP Multimedia Subsystem (IMS).
European Telecommunications Standards Institute (ETSI), Telecommunications and Internet Converged Services and Protocols for Advanced Networking (TISPAN) standardisation group, has published a document draft ETSI DTS TISPAN-01002-NGN V0.1.7 (2005-03) that describes requirements for Public Switched Telephone Network (PSTN)/Integrated Services Digital Network (ISDN) services in a communication network using Session Initiation Protocol (SIP). The document defines a recommended set of basic PSTN/ISDN simulation services which will be supported by the TISPAN Next Generation Network (NGN) Release 1 in connection with other networks as a basis for the definition of the network capabilities required. The purpose is to cover transition from PSTN/ISDN networks towards NGN networks and enable proper interconnection between the existing and coming networks.
An example of a service defined in the above-referred standard specification is an Advice of Charge (AoC) supplementary service which purpose is to provide a served user with information about the charging rates at the time of communication establishment or during the communication in the case of charging rates changes.
Another example of a supplementary service defined in the same standard specification is Terminating Identification Presentation (TIP). The TIP simulation service provides the originating party with the possibility of receiving asserted information in order to identify the connected party. In addition to the asserted identity information, the Connected Identity may include address information generated by the connected user and transparently transported by the network. Although normally an originating party knows to whom the party is calling, in case a called party has activated Communication session Deflection (CD) service, the originating party normally does not know to whom the called party has forwarded their communication. However, the called (forwarding) user may select an option that the originating user is notified of communication forwarding and optionally that also the ‘forwarded-to’ address is transmitted to the originating user. In this case the originating user will receive forwarding notification and optionally the connected user's identity when the communication is answered.
A further example of a communication supplementary service is Reverse Charging Service (REV) defined in International Telecommunication Union Telecommunication Standardization Sector (ITU-T) standard Q.86.3. The reverse charging supplementary service allows a calling user, on a per-call basis, to request reverse charging at the call set-up time and the called user to accept or reject the charges in the set-up response. If the called user accepts the request, the network starts charging the called user with notification of acceptance to the calling user and proceeds with the call. If the called user rejects or ignores the request, the network notifies the calling user and disconnects the call.
The above described services and several other supplementary services have been standardised by ITU and ETSI for Circuit Switched (CS) communication networks. In Packet Switched (PS) communication networks more advanced and user-friendly control mechanism for these services are needed. For example, currently in SIP there is no mechanism defined for AoC supplementary service how, after sending a session setup request, the user could control the session, after receiving some charging related information, whether or not to proceed with the session setup. Also other standardised supplementary services lack of control mechanisms.